In order to perform high-resolution observation of a defect, a foreign substance, and the like of a circuit pattern formed on a substrate (for example, a semiconductor wafer, a liquid crystal substrate, or the like), it has been proposed to use a liquid immersion type objective lens, fill a gap between a tip of the objective lens and the substrate with a liquid such as water, and increase a numerical aperture of the objective lens according to a refractive index (>1) of the liquid (see, for example, patent document 1). It has been further proposed to dry a substrate by an organic solvent, an air knife, or the like after the liquid immersion observation of the substrate and return the dried substrate to a cassette.
Patent Document 1: Japanese Unexamined Patent Application Publication No 2005-83800